1. Field of the Invention
This invention relates to microscopes, and more particularly to improvements in portions including a construction of changing over objective lens barrels.
2. Description of the Prior Art
In these days of requiring accuracies in the order of microns, microscopes, particularly industrial microscopes, have been remarkably popularized in the various industrial fields, have come into wide use ranging from the surface inspection of metal structures to IC (integrated circuit) outer appearance inspection. Further, the shapes of articles to be inspected are widely varied.
In general, the microscope is constructed such that a plurality of objective lenses are changed from one over to another for observation, and the conventional objective lens change-over construction is of such an arrangement that an objective lens barrel in use is aligned with an inspection optical axis, other objective lens barrels in non-use are inclined to the inspection optical axis in a manner to escape from the inspection optical axis, and an axis of rotation of a rotary member secured thereto with a plurality of objective lenses described above is inclined to the inspection optical axis.
In consequence, other objective lens barrels in non-use are protruded either to a direction of an operator or a direction opposite thereto, whereby the barrels interfere with the operations, and moreover, necessitate a turning mechanism to be complicated and rugged, thus proving to be uneconomical.
Further, the conventional change-over construction has raised the following new problems with the increase in the scope of the articles to be tested. Namely, when an article and/or a jig for holding the article is of a shape being not flat and having irregularities thereon and a surface to be inspected is present in a recess of a product, there are many cases where the forward end of the barrel impinges on the article and the like in changing one objective lens barrel over to another. This is because the forward end of the barrel moves drawing a circular arc, and, during the change-over, the forward end of the barrel approaches a mount in accordance with the rotation thereof. On the other hand, it may be contrived that, in order to avoid this, in changing from one barrel over to another, the mount is temporarily lowered, and thereafter, raised again. However, such a method as described above is disadvantageous in that the efficiency of inspection is lowered to a considerable extent.
Now, in these days of requiring the functional expansion of the microscopes, the major theme of this functional expansion includes the visual inspection and the easy recording through the connection of a three lens barrel with a camera, a television camera, a projector or the like.
However, the conventional microscopes have been constructed such that the change in the combination between the major structural elements, such as the replacement of illumination systems, is made easy and major constructions are fixed to facilitates selection of an optimum system for each of the uses. As a result, there have been many cases where the proper characteristics of the microscopes are adversely affected along with the functional expansion described above.
One of such cases as described above is the construction of a mounting for the three lens barrel to the main body of the microscope. More specifically, as shown in FIGS. 1 and 2, the conventional construction for mounting the three lens barrel is of such an arrangement that, by utilizing overhung portions 2 formed at two positions spaced 120.degree. apart from each other on a main body 1 and a bolt 3 rotatably secured to a position spaced 120.degree. apart from the two overhung portions 2 therebetween on the main body, a groove 6 provided on the three lens barrel is engaged with the overhung portions 2, and thereafter, by utilizing an inclined surface 7 provided on the three lens barrel 5, the three lens barrel is urged by the bolt 3 against the overhung portions 2, so that the three lens barrel can be fixed. The above-described construction, being a simplified one suitable only to the easy mounting and detaching, is disadvantageous in that the heavy weight of the three lens barrel 5 and a television camera or the like, which is mounted thereto, necessitates the mounting operation to be instable. Further, there is a possibility of the fall-down of the three lens barrel 5, and, it is difficult to maintain the accuracy of positioning of the main body 1 with the three lens barrel 5. Further, during inspection, there has been such a problem that a deflection of the head of the operator leads to a deflection or a shift in position of the three lens barrel 5.
As shown in FIG. 3, prisms in the three lens barrel in the conventional ordinary microscope are formed of two 60.degree.-30.degree. rectangular prisms 100 and 200. With these rectangular prisms 100 and 200, an image of the article 300 to be inspected is separated into two images, including an image 400 of a set system, such as for a television camera and a photography camera and another image 500 of a visual system.
However, in the arrangement of the conventional prisms, not only the image 400 of the set system but also the image 500 of the visual system are inverted images, whereby the moving direction of the article 300, i.e. the table feeding direction is opposite to the moving direction in the visual image in the vertical direction, and, as the case may be, in the lateral direction, thereby adversely affecting the controllability. Particularly, in the IC outer surface inspection and the like, the shape, pattern and the like are repeated in four directions, whereby the trouble due to the difference from the feeding direction is significant, thus disadvantageously lowering the efficiency of inspection to a considerable extent.